As glycolipid metabolic disorders, GM1 gangliosidosis, Morquio-B disease, Krabbe's disease, Fabry's disease, Gaucher's disease, Tay-Sachs disease, Sandhoff disease, fucosidosis and the like are conventionally known. These diseases are those caused by the result of mutation of various glycolytic enzymes. Among them, GM1 gangliosidosis, Morquio-B disease and Krabbe's disease are diseases caused by the loss of the enzyme activity of β-galactosidase due to its mutation, and Gaucher's disease is a disease caused by the loss of the activity of β-glucosidase due to its mutation. However, medicaments effective for these diseases have not been developed yet.
By the way, Fabry's disease is a disease caused by the mutation of α-galactosidase, and it is known that an α-galactosidase inhibitor could become a therapeutic drug of this disease (Nature Medicine, 5(1), 112-115 (1999)). It is considered that the aforementioned enzyme inhibitor recovers the enzyme activity by a mechanism in which the strong enzyme inhibitor stabilizes a mutant enzyme protein expressed in cells at a low concentration.
In the case that an enzyme inhibitor can stabilize a mutant enzyme protein, it is highly possible that a β-galactosidase inhibitor is effective as a therapeutic drug for diseases induced by the mutation of β-galactosidase, and it is highly possible also that a β-glucosidase inhibitor is effective as a therapeutic drug for diseases induced by the mutation of β-glucosidase.
However, a β-galactosidase inhibitor or β-glucosidase inhibitor which specifically and strongly inhibits human β-galactosidase or β-glucosidase has not been obtained so that the aforementioned therapeutic drug has not been developed yet.